[gal/Wh] The measure of overall pool filter pump efficiency in units of gallons per watt-hour, as determined using the applicable test method in Section 4.1.2. Energy factor is analogous to other energy factors such as miles per gallon. Energy factor (EF) is calculated as: EF (gal/Wh) = flow rate (gpm) * 60 รท power (watts) (ANSI/APSP/ICC-15 2011).